Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/44—Resins; rubber; leather
  • G01N33/442—Resins, plastics
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K31/00—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups
  • B23K31/12—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups relating to investigating the properties, e.g. the weldability, of materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
  • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
  • B29C65/14—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation
  • B29C65/16—Laser beams
  • B29C65/1629—Laser beams characterised by the way of heating the interface
  • B29C65/1635—Laser beams characterised by the way of heating the interface at least passing through one of the parts to be joined, i.e. laser transmission welding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
  • B29C65/78—Means for handling the parts to be joined, e.g. for making containers or hollow articles, e.g. means for handling sheets, plates, web-like materials, tubular articles, hollow articles or elements to be joined therewith; Means for discharging the joined articles from the joining apparatus
  • B29C65/7858—Means for handling the parts to be joined, e.g. for making containers or hollow articles, e.g. means for handling sheets, plates, web-like materials, tubular articles, hollow articles or elements to be joined therewith; Means for discharging the joined articles from the joining apparatus characterised by the feeding movement of the parts to be joined
  • B29C65/7879—Means for handling the parts to be joined, e.g. for making containers or hollow articles, e.g. means for handling sheets, plates, web-like materials, tubular articles, hollow articles or elements to be joined therewith; Means for discharging the joined articles from the joining apparatus characterised by the feeding movement of the parts to be joined said parts to be joined moving in a closed path, e.g. a rectangular path
  • B29C65/7882—Means for handling the parts to be joined, e.g. for making containers or hollow articles, e.g. means for handling sheets, plates, web-like materials, tubular articles, hollow articles or elements to be joined therewith; Means for discharging the joined articles from the joining apparatus characterised by the feeding movement of the parts to be joined said parts to be joined moving in a closed path, e.g. a rectangular path said parts to be joined moving in a circular path
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
  • B29C65/82—Testing the joint
  • B29C65/8253—Testing the joint by the use of waves or particle radiation, e.g. visual examination, scanning electron microscopy, or X-rays
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
  • B29C65/82—Testing the joint
  • B29C65/8261—Testing the joint by the use of thermal means
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/01—General aspects dealing with the joint area or with the area to be joined
  • B29C66/05—Particular design of joint configurations
  • B29C66/10—Particular design of joint configurations particular design of the joint cross-sections
  • B29C66/11—Joint cross-sections comprising a single joint-segment, i.e. one of the parts to be joined comprising a single joint-segment in the joint cross-section
  • B29C66/112—Single lapped joints
  • B29C66/1122—Single lap to lap joints, i.e. overlap joints
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/01—General aspects dealing with the joint area or with the area to be joined
  • B29C66/05—Particular design of joint configurations
  • B29C66/10—Particular design of joint configurations particular design of the joint cross-sections
  • B29C66/11—Joint cross-sections comprising a single joint-segment, i.e. one of the parts to be joined comprising a single joint-segment in the joint cross-section
  • B29C66/114—Single butt joints
  • B29C66/1142—Single butt to butt joints
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/50—General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
  • B29C66/51—Joining tubular articles, profiled elements or bars; Joining single elements to tubular articles, hollow articles or bars; Joining several hollow-preforms to form hollow or tubular articles
  • B29C66/53—Joining single elements to tubular articles, hollow articles or bars
  • B29C66/534—Joining single elements to open ends of tubular or hollow articles or to the ends of bars
  • B29C66/5344—Joining single elements to open ends of tubular or hollow articles or to the ends of bars said single elements being substantially annular, i.e. of finite length, e.g. joining flanges to tube ends
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/50—General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
  • B29C66/51—Joining tubular articles, profiled elements or bars; Joining single elements to tubular articles, hollow articles or bars; Joining several hollow-preforms to form hollow or tubular articles
  • B29C66/54—Joining several hollow-preforms, e.g. half-shells, to form hollow articles, e.g. for making balls, containers; Joining several hollow-preforms, e.g. half-cylinders, to form tubular articles
  • B29C66/542—Joining several hollow-preforms, e.g. half-shells, to form hollow articles, e.g. for making balls, containers; Joining several hollow-preforms, e.g. half-cylinders, to form tubular articles joining hollow covers or hollow bottoms to open ends of container bodies
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/50—General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
  • B29C66/61—Joining from or joining on the inside
  • B29C66/612—Making circumferential joints
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
  • B29C66/73—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset
  • B29C66/739—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset
  • B29C66/7392—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of at least one of the parts being a thermoplastic
  • B29C66/73921—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of at least one of the parts being a thermoplastic characterised by the materials of both parts being thermoplastics
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N25/00—Investigating or analyzing materials by the use of thermal means
  • G01N25/72—Investigating presence of flaws
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
  • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
  • B29C65/14—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation
  • B29C65/16—Laser beams
  • B29C65/1629—Laser beams characterised by the way of heating the interface
  • B29C65/1664—Laser beams characterised by the way of heating the interface making use of several radiators
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/90—Measuring or controlling the joining process
  • B29C66/95—Measuring or controlling the joining process by measuring or controlling specific variables not covered by groups B29C66/91 - B29C66/94
  • B29C66/952—Measuring or controlling the joining process by measuring or controlling specific variables not covered by groups B29C66/91 - B29C66/94 by measuring or controlling the wavelength
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2031/00—Other particular articles
  • B29L2031/712—Containers; Packaging elements or accessories, Packages
  • B29L2031/7146—Battery-cases

Definitions

• the present invention relates to thermal imaging of plastic welds, and more particularly to infra-red thermal imaging of thermoplastic components used in battery module enclosures.
• Battery module enclosures house one or more battery cells that are utilized to provide electrical power.
• a battery module enclosure may include multiple battery cells connected in series to provide a desired voltage.
• the battery cells comprise liquid materials such as potassium hydroxide and require airtight sealing from an exterior of the battery module as well as between individual cells to prevent a short-circuit condition.
• the battery modules are often utilized in physically unstable environments such as vehicles for hybrid electric applications. Therefore, battery module enclosures commonly comprise thermoplastic materials such as polymeric blends. Since the battery module enclosures typically include at least two interfacing components, welding is often required to create a seal between the multiple components.
• a thermal imaging system for a battery module enclosure that includes first and second battery module enclosure components between which a weld is formed according to the present invention includes a thermal imaging camera that focuses on the first and second battery module enclosure components within a predetermined amount of time after the weld is formed and that acquires a thermal signature.
• a control module includes an image processing module that receives the thermal signature and that locates a predetermined reference point in the thermal signature.
• An image comparison module receives the thermal signature and uses the predetermined reference point to compare the thermal signature to a template signature in order to verify structural integrity of the weld.
• the thermal imaging camera is an infra-red thermal imaging camera.
• the image processing module utilizes an image processing algorithm that locates a structural feature that is common to both of the thermal and template signatures.
• the first and second battery module enclosure components comprise polymeric thermoplastics.
• the battery module enclosure houses at least one battery cell for a hybrid electric vehicle.
• a laser source focuses a laser beam on the first and second module enclosure components in order to form the weld.
• the first and second module enclosure components are fixed on a turntable that includes a motor.
• the control module includes a turntable module that adjusts a position of the turntable so that the first and second module enclosure components are located within a path of the laser beam when the laser source forms the weld and so that the first and second module enclosure components are within a field of view of the thermal imaging camera when the thermal imaging camera acquires the thermal signature.
• the image comparison module computes a relative measure of deviation of the thermal signature from the template signature and identifies the weld as defective when the relative measure of deviation is greater than a predetermined value.
• a data module stores the template signature.
• the image comparison module stores the thermal signature and a weld integrity value that is associated with the thermal signature in the data module after the image comparison module verifies structural integrity of the weld.
• a data analysis module generates weld integrity statistics based on a plurality of weld integrity values that are stored in the data module.
• FIG. 1 is a functional block diagram of a thermal imaging system for plastic enclosure components of a battery module according to the present invention
• FIG. 2A is a front view of an exemplary single-cell battery module enclosure
• FIG. 2B is a side cross-section of the single-cell battery module enclosure illustrating interfaces between plastic battery module enclosure components
• FIG. 2C is a scaled partial view of FIG. 2B illustrating a weld made between the plastic enclosure components using laser welding;
• FIG. 3A is a first cross-section of the single-cell battery module enclosure illustrating welding along an interface between two plastic enclosure components
• FIG. 3B is a thermal signature of the single-cell battery module enclosure of FIG 3A from a top view perspective following a welding procedure
• FIG. 4 illustrates an exemplary thermal signature gradient that identifies visual image fluctuations in thermal signatures due to temperature variations
• FIG. 5A is a second cross-section of the single-cell battery module enclosure illustrating a defect in the plastic enclosure components
• FIG. 5B is a thermal signature of the single-cell battery module enclosure of FIG. 5A from a top view perspective that illustrates a visual inconsistency at the defective region;
• FIG. 6 is a flowchart illustrating steps performed by the thermal imaging system to detect defective welds.
• module refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.
• ASIC application specific integrated circuit
• processor shared, dedicated, or group
• memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.
• an exemplary thermal imaging system 10 for a battery module enclosure 12 includes a laser source 14, an infra-red thermal imaging camera 16, and a turntable 18.
• Plastic enclosure components 12 that are desired for welding are fixed to the turntable 18.
• the turntable 18 may move the plastic enclosure components 12 between three different positions. At a first position, the plastic enclosure components 12 are fixed to the turntable 18.
• the plastic enclosure components 12 are moved to a second position where the laser source 14 generates welds at junctions between two or more plastic enclosure components 12.
• the plastic enclosure components 12 are moved to a third position where the infra-red thermal imaging camera 16 captures a thermal signature in order to verify the integrity of the welds.
• a control module 20 controls operation of the thermal imaging system 10.
• the control module 20 includes a turntable control module 22 that communicates with a motor 24 of the turntable 18 and adjusts a position of the turntable 18 during welding and thermal imaging of the plastic enclosure components 12.
• the turntable control module 22 may be programmed to rotate the turntable 18 a predetermined number of degrees between each of the positions.
• a laser control module 26 controls operation of the laser source 14.
• the laser control module 26 turns the laser source 14 on and off and may adjust operational parameters of the laser source 14 such as a wavelength of a laser beam 28 that the laser source 14 emits.
• a camera control module 30 controls operation of the infra-red thermal imaging camera 16.
• the camera control module 30 turns the infra-red thermal imaging camera 16 on and off and may adjust operational parameters such as resolution and zoom.
• the plastic enclosure components 12 comprise thermoplastics such as polymeric blends. Since thermoplastics are poor conductors, the weld temperatures of the plastic enclosure components 12 remain consistent for a period of time. Therefore, the infra-red thermal imaging camera 16 preferably acquires thermal signatures of the welded plastic enclosure components 12 within a predetermined amount of time after the welding procedure is completed. For example, the infra-red thermal imaging camera 16 may be set to acquire the thermal signatures within five seconds after a welding procedure is performed.
• An image processing module 32 receives thermal signatures corresponding to the plastic enclosure components 12 from the infra-red thermal imaging camera 16.
• a database 34 includes a template signature corresponding with plastic enclosure components 12 that have predetermined satisfactory welds.
• a template signature may correspond with plastic enclosure components 12 that are rigorously inspected using microscopic technology to ensure satisfactory welds.
• the template signature includes one or more reference points that correspond with structure that is common to both the template signature and other potential thermal signatures. Therefore, the image processing module 32 utilizes an image processing algorithm to locate a reference point on a thermal signature that corresponds with a reference point on the template signature.
• the reference point may be a visible surface or edge of the plastic enclosure components 12.
• An image comparison module 36 receives the thermal signature from the image processing module 32 and the template signature from the database 34.
• the image comparison module 36 compares the thermal and template signatures to detect defective plastic enclosure components 12 or weak or non-existent welds.
• the image comparison module 36 may detect visual inconsistencies in the thermal signature along junctions where the plastic enclosure components 12 are welded. Based on the comparison, the image comparison module 36 determines whether the plastic enclosure components 12 are satisfactory or unsatisfactory.
• the image comparison module 36 may compute a relative measure of deviation of the thermal signature from the template signature.
• a satisfactory thermal signature may correspond with a relative measure of deviation that is less than or equal to a predetermined value.
• the predetermined value may be adjusted depending on a desired tolerance with which to inspect the plastic enclosure components 12.
• the image comparison module 36 stores the thermal signature in the database 34 with the associated satisfactory or unsatisfactory identifier.
• the control module 20 includes a data analysis module 38 that reads stored thermal signature test results in the database 34 and generates weld integrity statistics. For example, the data analysis module 38 may track the relative rate of occurrence of defective welds for quality control purposes.
• an exemplary battery module 46 includes an inner cavity 48 that houses a battery cell.
• the inner cavity 48 is defined by multiple plastic enclosure components 50 that interface and are welded together along junctions between the plastic enclosure components 50.
• FIG. 2C illustrates an enlarged view 52 of a junction 54 between side and top plastic enclosure components 50-3 and 50-2, respectively, of the battery module 46.
• a through transmission laser welding (TTLW) process is used to focus the laser beam 28 at the junction 54.
• the laser source 14 may include a plurality of laser beams 28 that are utilized to continuously illuminate a desired area, although other laser source configurations are possible.
• a melt pool 56 forms within a heat zone 58, which leaves a structural bond between the plastic enclosure components 50-2 and 50- 3 when the laser source 14 is turned off and the melt pool 56 cools.
• thermoplastics typically have a low conductivity and the laser source 14 has high focusing capabilities, the heat zone 58 is relatively small and presents little risk to components housed in the inner cavity 48.
• battery module 46 illustrated in FIGs. 2A-2C is a single-cell battery module 46, those skilled in the art can appreciate that battery modules 46 may include multiple battery cells that are individually isolated and connected in series.
• FIGs. 3A and 3B in order for a laser beam 28 to reach the junction 54 between plastic enclosure components 50, at least one of the plastic enclosure components 50-4 and/or 50-3 is transmissive to a wavelength of the laser beam 28.
• the wavelength of the laser beam 28 is between 800 nm and 1100 nm, although other wavelengths are possible.
• the laser beam 28 penetrates plastic enclosure component 50-3 to create the heat zone 58 at the junction 54 between the plastic enclosure components 50.
• FIG. 3A illustrates plastic enclosure components 50 that are free of defects prior to welding, and welds are made along a perimeter of the plastic enclosure components 50 to seal the battery module 46 during the welding process.
• FIG. 3B shows a top view of the thermal signature 66 for the plastic enclosure components 50. Temperature differences at weld points 68 along the perimeter of the battery module 46 are indicated by fluctuating colors on the thermal signature 66.
• an exemplary thermal signature gradient 76 illustrates the appearance of varying temperatures on thermal signatures 66.
• temperatures below room temperature do not stand out in the thermal signature 66 and temperatures required for thermoplastic welding appear very dark or opaque. Therefore, colors remain consistent with expected temperatures along weld points 68 as illustrated in FIG. 3B.
• Interior portions 78 (as shown in FIG. 3B) of the weld points 68 appear very dark along the perimeter of the plastic enclosure components 50, and the colors lighten when moving away from the interior portions 78.
• FIG. 5B shows a top view of a thermal signature 90 for the battery module 86 of FIG. 5A.
• the consistency in color of the thermal signature 90 along the weld points 68 is broken at an area 92 where the chip 88 is located.
• the typically dark color of the interior portion 78 of the weld points 68 is missing and is replaced with a lighter color consistent with outer portions 94 of weld points 68.
• the image processing algorithm executed by the image processing module 32 detects the inconsistency in the thermal signature 90 and identifies the battery module 86 as defective before storing the thermal signature 90 in the database 34.
• a thermal imaging algorithm begins in step 102.
• control determines whether the next plastic enclosure components 50 desired for welding are in position. If false, control loops to step 104. If true, the turntable control module 22 adjusts a position of the turntable 18 so that the plastic enclosure components 50 are situated under the laser source 14 for welding in step 106.
• the laser control module 26 activates the laser source 14 to generate the welds.
• the turntable control module 22 adjusts a position of the turntable 18 so that the plastic enclosure components 50 are situated within a field of view of the infra-red thermal imaging camera 16.
• the camera control module 30 activates the infra-red thermal imaging camera 16 in order to acquire a thermal signature 90 of the plastic enclosure components 50.
• step 114 the image processing module 32 receives the thermal signature 90 and locates a reference point that is consistent with the template signature 66.
• step 116 the image comparison module 36 compares the thermal and template signatures 90 and 66, respectively, and computes a relative measure of deviation of the thermal signature 90 from the template signature 66.
• step 118 control determines whether the relative deviation is greater than a predetermined value. If true, control proceeds to step 120. If false, the image comparison module 36 identifies the battery module 86 as satisfactory in step 122 and control proceeds to step 124. In step 120, the image comparison module 36 identifies the battery module 86 as defective and control proceeds to step 124. In step 124, the image comparison module 36 stores the thermal signature 90 in the database 34 and control ends.
• the thermal imaging system 10 of the present invention is utilized to verify proper welding of plastic enclosure components 50 of battery modules 86 such as battery cells for hybrid electric vehicles.
• the thermal imaging system 10 is non-destructive and may be completely integrated with the laser welding process in order to identify defective welds immediately, which lowers costs and reduces manufacturing times.

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• 2005
  • 2005-08-24 US US11/211,021 patent/US8162020B2/en not_active Expired - Fee Related
• 2006
  • 2006-08-24 MX MX2008002579A patent/MX2008002579A/es active IP Right Grant
  • 2006-08-24 EP EP20060802231 patent/EP1929283B1/de not_active Expired - Fee Related
  • 2006-08-24 WO PCT/US2006/033039 patent/WO2007025021A2/en active Application Filing
  • 2006-08-24 JP JP2008528141A patent/JP4884472B2/ja not_active Expired - Fee Related
  • 2006-08-24 CA CA 2620084 patent/CA2620084A1/en not_active Abandoned
  • 2006-08-24 CN CNA2006800395029A patent/CN101297194A/zh active Pending
• 2008
  • 2008-12-09 US US12/330,787 patent/US7959353B2/en not_active Expired - Fee Related

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